CARLSBAD  The debate over affordable housing and “smart growth” goes to the Carlsbad Planning Commission on Wednesday, when the panel is set to consider a 656-home development proposed for the site of an old rock quarry on the city’s border with Oceanside.

City staffers have recommended approval of the Quarry Creek proposal. The developer calls the project an example of smart growth and the perfect place to concentrate affordable housing, while opponents say it is just the opposite.

Regional planners define smart growth as building homes close to shopping, services, transit centers and other needs, largely to lessen time and resources spent on commuting and to make neighborhoods more dynamic.

The 156-acre Quarry Creek site is along the southern side of state Route 78 between El Camino Real and College Boulevard. The Buena Vista Creek crosses the property and the historically significant El Salto waterfall is on the eastern end.

“We think we are a shining example of smart growth in the region,” said Todd Galarneau, project manager for the Corky McMillin Companies, a builder in the area for more than 50 years.

Most of the homes will be built on land that was used as a rock quarry for 50 years, Galarneau said, and the rest will be on undeveloped land long designated for housing by the city. The site is near public transportation, a shopping center, MiraCosta College and other resources, he added.

Opponents of the project, such as Diane Nygaard of the environmental nonprofit group Preserve Calavera, disagree.

“This is not smart growth,” Nygaard said. “This is dense development adding to traffic congestion.”

The large number of homes would be devastating to the natural resources in the small valley along the creek, she said, and the additional residents would further compound traffic in an area that’s already congested.

Carlsbad Senior Planner Van Lynch said the developer is working with Carlsbad and Oceanside on ways to handle the increased traffic.

One of the improvements being considered to help handle the traffic is additional right-turn lanes at the intersection of College and Marron, he said.

McMillin’s plan calls for the housing, which would all be apartments or condominiums, to be built in two areas covering 50 of the 156 acres. There would also be community areas such as a day-care building and a recreation site. About 88 acres, or 56 percent of the property, would be set aside as open space, including the creek and the waterfall.

A portion of the property designated for the highest density development, a minimum of 20 units per acre, is on the northern side of Buena Vista Creek, where McMillin’s plan calls for 332 dwellings on 18.2 acres.

The rest of the homes, 325, would be built in two separate areas totaling 37 acres stretching the length of the property on the south side of the creek.

Nygaard, who lives in Oceanside just across the border from Carlsbad, said she’d like to see a compromise that reduces the number of homes and keeps them on the eastern end of the property that was the quarry.

“It’s just too much development for that particular location,” she said.

Galarneau said McMillin’s proposal is really the community’s plan, based in part on 80 to 100 meetings with residents and officials from the cities, state and federal agencies and other interested parties.

The development has two access points — Marron and Haymar roads — he said, though both connect only to College Boulevard. Those two roads will be connected by a bridge the developer will build across the creek to create a loop through the living area.

There is no plan to extend Marron Road west to El Camino Real, he said, largely because it would have to cross the Buena Vista Creek ecological area.

The city’s zoning allows as many as 788 homes on the 156 acres, Galarneau said.

“We have not only followed the rules, we have exceeded the rules in a lot of respects,” he said.

All of the units will meet the state’s requirement for affordable housing, he said.

“A really important part of this is that if those are not placed on the Quarry Creek site, then the city will have to identify other areas to locate those units,” Galarneau said.

More than 500 of the homes will be what’s considered “density-based” affordable housing and will be rented or sold at current market rates.

Density-based low-income housing is based on the theory that more units per acre lowers the cost of housing. Only about 15 percent of the housing will be “income-restricted” housing reserved for people with low incomes.

Once the city approves the project, Galarneau said, grading and site preparations should begin late this year or early in 2014, and buildings are likely to start going up in 2015.

The residential construction is the second phase of a development McMillin has been working on for more than a decade.

The first phase was the shopping center that straddles Marron Road on the western side of College Boulevard, with a Walmart, Kohls, Albertsons and smaller shops and restaurants. That portion of the project is in Oceanside.